* cygwin.din: Export _getmode and getmode to allow querying of binary state of

* cygwin.din: Export _getmode and getmode to allow querying of binary state of
an fd.
* external.cc (cygwin_internal): Add handling of perfile_table setting.
* fhandler.cc (perfile_table): New global.
(fhandler_base::get_default_fmode): New method to return a file's default mode
based on its name.
(fhandler_base::open): Use get_default_mode method to determine a file's mode.
Record file mode in file flags.
* fhandler.h (fhandler_base): Declare get_default_fmode
* syscalls.cc (getmode): New function.
* sys/cygwin.h (__cygwin_perfile): New structure.
(cygwin_getinfo_types): Move outside of WINVER conditional.
(per_process): Move inside of WINVER conditional.